Did a curious look myself now at the referred location, but it doesn't work for me either...
Pages 5 to 7 simply appear empty.
And I use FF 3.6.3 normally. I even tried with IE, but no luck. This is a really funny bug. :-D
____________Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@HeidelbergMy BOINC-Stats

What content are you seeing on those pages? I.e. how many threads and what are the top and bottom thread on each page? Are there any pages with less threads than others (apart, of course, from the last ones that are empty)?

Well, I first thought everything up to page 5 would have been correct.
But on a closer look now I found out that on page 1-3 are 50 threads displayed (as default I guess), but on page 4 only 32. And the last one of them is session 259.

Edit:
Would be funny to see what will happen if a new session thread is opened.
Maybe 259 disappears and 255 is the last one then.
____________Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@HeidelbergMy BOINC-Stats

It seems it may be related to spam that has been deleted by moderation - so the spam threads count in as being there but don't actually show up for non-admins.

That much spam-threads in the session comment section that it may fill up 3 sites? Can't imagine that...
Accidentally found another source while browsing through the sections:
"General talk" page 4 is also empty, while page 3 has exactly 50 threads...
____________Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@HeidelbergMy BOINC-Stats